The present invention relates to a piston arrangement for a shock absorber of the type used in the wheel suspension for automotive vehicles. Piston arrangements of this type conventionally incorporate a piston which is mounted for reciprocatory movement within the shock absorber housing, this piston being carried by a piston rod on which the piston is mounted so as to be axially non-displaceable relative thereto. The piston has one or more channels through which a damping medium may flow when the piston is axially displaced in the shock absorber, there being two valves--a main or working valve and a check valve--for controlling the flow of the damping medium when the piston is moved in opposite axial directions, respectively. Each valve has a valve element which opens against a spring force, depending on the direction of axial movement of the piston and therefore on the direction of flow of the medium. The closure element of one of the two valves is in the form of at least one disc whereas the closure element of the other valve is in the form of a sleeve which surrounds the piston rod and which has a flange that is exposed to the pressure of the medium when the valve is opened.
In conventional piston arrangements of the above type, the sleeve is in the shape of a small cup which, when the valve is closed, overlies the flow channels in the piston which are arranged relatively well within the interior of the piston. The piston generally has additional flow channels which are radially outward of the first-mentioned flow channels, these further channels being covered by at least one disc when the respective valve is closed.
A number of advantages are obtained if the closure elements are constituted by disc-type springs rather than by rigid discs. For one thing, it is easier and less expensive to manufacture the mechanism. Furthermore, by selecting disc-type springs having appropriate parameters, the shock absorber can be given virtually any desired damping characteristic, even a quite complicated damping characteristic. On the other hand, disc-type springs have the drawback that they take up a relatively large amount of space, particularly if the shock absorber is to have a favorable damping characteristic. Conventionally, some space saving is sought to be realized by positioning the flow channels associated with the two valves radially next to each other, so that when the valve which includes the cup-shaped closure element is open, the damping medium will be supplied by way of a flow path which is interiorly of the disc.
It is, therefore, the object of the present invention to provide a piston arrangement of the above general type in which the parts are so arranged as to require a minimum of space within the cylinder of the shock absorber.